Energy-saving technologies contribute to improving our environment, saving resources, and bringing cost benefit. At present the following approaches are available for energy saving of a mobile communication network: 1) the number of base station sites is optimized without influencing coverage, capacity and quality of service; 2) methods for effectively increasing utilization ratio of energy sources and reducing power consumption of devices are sought; and 3) sustainable energy resources, e.g., wind energy, solar energy, etc., are researched and developed.
For those energy-saving technologies in the approach 2), the concept of Energy Saving Management (ESM) has been proposed, where ESM refers to optimization of a resource utilization ratio of the entire network or a part thereof. ESM initiates appropriate actions through collecting and evaluating relevant information over the network to adjust network configuration, thereby satisfying service demands while saving the energy.
For a self-optimized network, an energy-saving entity can be roughly divided into the following three structures: distributed architecture, where a network element collects necessary information for a self-optimization process with no need for participation of Operation Administration and Maintenance (OAM); centralized architecture, where OAM collects information from a network element for triggering an energy-saving algorithm and then decides subsequent actions of the network element; and hybrid architecture, where both of the foregoing schemes are used in combination.
An energy-saving solution includes two basic processes:
1) Energy saving activation: a cell of an evolved Node B (eNB) is disabled or the use of a part of material resources is limited for the purpose of saving energy, and the corresponding eNB enters into an energy-saving state; and
2) Energy saving deactivation: the disabled cell is enabled or the limited use of material resources is resumed to thereby satisfy increased service demands and Quality of Service (QoS) demands, and the corresponding eNB returns to a normal state from the energy-saving state.
Energy-saving actions include: disabling/enabling a cell; disabling/enabling a carrier; disabling/enabling a transceiver; disabling/enabling a Home eNB (HeNB) and others.
FIG. 1 is a structure diagram of a network of heterogeneous systems where a Long Term Evolution (LTE) system and an Advanced LTE (LTE-A) system coexist, a User Equipment (UE), a radio access network and a Core Network (CN) constitute the architecture of the entire network of heterogeneous systems, and the UE supports communication with an eNB via an LTE-Uu interface, communication with a Node B via a UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access Network (UTRAN)-Uu interface and communication with a Base Transceiver Station (BTS) via a GSM (Global System for Mobile Communications) EDGE (Enhanced Data Rate for GSM Evolution) Radio Access Network (GERAN)-Um interface.
The eNB accesses a Mobility Management Entity (MME) in the CN via an S1 interface, the Node B communicates with a Radio Network Controller (RNC) via an Iub interface, the BTS communicates with a Base Station Controller (BSC) via an Abis interface, the RNC is connected to the BSC via an Iur-g interface, and the RNC and the BSC access a Serving GPRS Support Node (SGSN) in the CN respectively via Iu interfaces. The SGSN and the MME in the CN perform interaction of an ESM control message.
At present, energy saving is performed by using the distributed architecture in the LTE system, that is, a basic base station with a wide coverage area decides whether to activate an energy-saving cell in the coverage area of the basic base station according to current load condition, and the energy-saving cell can disable a transmitter by itself to enter into an energy-saving state when its load is very low.
For a cell with three sectors, for example, there are four transceivers in each sector, and devices at the Radio Access Network (RAN) side are intended for a demand during peak hours, so twelve transceivers stay in an activation state all the time, but this may not be required during low-service hours (e.g., a midnight). Thus an energy source control mechanism is introduced, where each sector is provided with a transceiver capable of covering the sector, and a service demand can be satisfied so long as this transceiver is kept in a standby state during low-service hours. If this energy-saving strategy is applicable to all the eNBs, considerable energy sources can be saved without influencing quality of service.
However a basic base station with a large coverage area has to be deployed in the foregoing energy-saving mechanism, but a waste of resources may result from the coverage area of the basic base station being too large, while service losses of other energy-saving cells may result from the coverage area of the basic base station being not sufficiently large after the other energy-saving cells disable transceivers in an energy-saving state.
An energy saving compensation technology used to compensate service losses of energy-saving cells is absent in the existing LTE energy-saving solution, and the existing distributed architecture can not be applied to different application scenarios flexibly.